Kennedy’s the one to watch, even if his name appears nowhere in a trial judge’s 138-page opinion issued Wednesday striking down California’s Proposition 8 ban on gay marriages. Nonetheless, Kennedy’s previous decisions were cited 16 times in U.S. District Judge Vaughn Walker’s ruling that Proposition 8 violates the Constitution.

“It seems the issue will clearly be close, and on close cases (Kennedy) tends to be in the middle,” said Carl Tobias, a University of Richmond law professor.

Kennedy wrote gay-friendly opinions in a 1996 case striking down a Colorado ballot measure and a 2003 case striking down a Texas law that banned gay sodomy.

He says he hasn’t tipped his hand on gay marriage, stressing that the 2003 decision “does not involve whether the government must give formal recognition to any relationship that homosexual persons seek to enter.”

However, some hope — and some fear — that Kennedy’s sympathies are already clear.

Kennedy’s opinion “dismantles the structure of constitutional law that has permitted a distinction to be made between heterosexual and homosexual unions, insofar as formal recognition in marriage is concerned,” Justice Antonin Scalia wrote in a 2003 dissent.

The Supreme Court could look different by the time the gay marriage case arrives, though. Some intervening steps, not all of them predictable, also may shape the case’s outcome.

A randomly selected three-judge panel of the San Francisco-based 9th U.S. Circuit Court of Appeals will review Walker’s decision first. Eleven of the 9th Circuit judges then could review the appellate panel’s work, in turn, in what’s called an en banc decision.

The appellate reasoning and the resulting posture of the case could nudge justices one way or another, though the Supreme Court never hesitates to show who’s boss. During the last two years, the Supreme Court reversed 9th Circuit decisions in 22 out of 31 cases.

The 9th Circuit’s briefing schedule released Thursday calls for all briefs to be submitted by late December. Oral arguments will come later.

Because the Supreme Court typically finishes setting its docket in mid-January, this means there won’t be time to hear any appeal before the term ends next June.

“We’re talking the 2011 term,” Tobias said.

At least one new justice, Elena Kagan, will have joined the court in the meantime. Kagan’s position on a gay marriage ban may have been foreshadowed by the position she took as Harvard Law School dean opposing the military’s ban on gays openly serving.

“I abhor the military’s discriminatory policy,” Kagan declared in a 2003 memo. “This policy is a profound wrong, a moral injustice of the first order.”

By 2011 there might be other court newcomers, too, whose views will shape the outcome.

The court’s oldest member now is 77-year-old Justice Ruth Bader Ginsburg, who’s battled cancer several times.

A Democratic president, Bill Clinton, appointed Ginsburg. Although she hasn’t hinted at retiring, her departure during President Barack Obama’s term could affect the gay marriage case. For instance: If Democrats lose some Senate seats this November, as appears likely, their weaker grip on the Senate could make Obama more likely to pick a moderate for the Supreme Court rather than an avowed liberal.

Still, for the foreseeable future, Kennedy is likely to be the go-to justice.